In patients with an elevated left ventricular filling pressure, the mitral A wave is diminished while the pulmonary venous A wave is augmented because of decreased left ventricular compliance. We examined whether an increase in the ratio of pulmonary venous to mitral A velocity might be a marker for an elevated mean pulmonary capillary wedge pressure. Forty-one patients who had left ventricular systolic dysfunction underwent transthoracic Doppler echocardiography simultaneously or within 24 hours of right heart catheterization. There were 29 men and 12 women 61 +/- 12 (mean +/- SD) years of age. Underlying heart disease was ischemic cardiomyopathy in 27 and nonischemic cardiomyopathy in 14 patients. The same Doppler-hemodynamic study was performed on 8 patients after optimal management of heart failure. The ratio of pulmonary venous to mitral A velocity correlated strongly with mean pulmonary wedge pressure (r = 0.72, P < .0001). When the cutoff value of the ratio was set at 0.5 or higher, the sensitivity for predicting a pulmonary capillary wedge pressure of 15 mm Hg or more was 88%, and the specificity was 80%. The serial Doppler-hemodynamic study showed that the ratio decreased markedly after treatment of heart failure. The value was 0.84 +/- 0.29 before treatment and 0.36 +/- 0.17 after treatment (P = .001). An increased ratio of pulmonary venous to mitral A velocity is a useful marker for elevated pulmonary capillary wedge pressure among patients with left ventricular systolic dysfunction.